Question

the speed of a Boat is in still water is 9 km per hr if the boat goes 54 km downstream in 4 hour find the speed of the stream

Answer 1

Speed of boat in still water = 9km/hr
Speed of boat downstream = 54 km / 4 hour = 13.5 km/hr
(Speed = Distance/time)

So, the speed of boat downstream will be the sum of the actual speed of boat and the speed of the stream
13.5 = 9 + Speed of the stream
Speed of the stream = 13.5 - 9 = 4.5 km/hr